The raising is pricing new shares at 27c each and comprises an $18 million placement - of which $13.1 million is going to existing shareholders, including Tribeca, and a $3 million share purchase plan.
The fundraising will take Tesoro's treasury to about $24 millon.
Testament to Tesoro's success of late is the difference in the placement quantum and pricing from the junior's last fund raising effort in June, when $4.4 million was raised by issuing new shares priced at 6c each.
Tesoro said the funds would go towards a 50,000m drill campaign, metallurgical testwork, and the commencement of a scoping study next year.
Tesoro owns 70% of El Zorro and can go to 80% by delivering a feasibility study.
The Ternera prospect has a mineralised zone of over more than 1500m of strike, up to 100m thick and down to 300m, "open in all directions".
Hits have included 98m grading 1.6 grams per tonne and 86m at 2.3gpt.
Share in Tesoro were down 3.5% to 28.5c, capitalising the company at $136 million.
The stock spiked to a high of 52.5c in October.
